//代码块复制按钮
.highlight{
  //方便copy代码按钮（btn-copy）的定位
  position: relative;
}
.btn-copy {
    display: inline-block;
    cursor: pointer;
    background-color: #eee;
    background-image: linear-gradient(#fcfcfc,#eee);
    border: 1px solid #d5d5d5;
    border-radius: 3px;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    -webkit-appearance: none;
    font-size: 13px;
    font-weight: 700;
    line-height: 20px;
    color: #333;
    -webkit-transition: opacity .3s ease-in-out;
    -o-transition: opacity .3s ease-in-out;
    transition: opacity .3s ease-in-out;
    padding: 2px 6px;
    position: absolute;
    right: 5px;
    top: 5px;
    opacity: 0;
}
.btn-copy span {
    margin-left: 5px;
}
.highlight:hover .btn-copy{
  opacity: 1;
}
